Sorry Rugby man but I'm sure if a real off world alien placed a implant of any kind inside of you it could not be traced. Just a guess but if they were to 'tag' you, my bet, is it would be biological in nature and microscopic in size.

i have one about same size which has migrated from lower back to shoulder over a number of years(following an experience of possible abduction)i believe it is biological in make up and it is a very distinct tablet shape,I am curious but whenever i have thought to get it looked at ,i get a "block" against doing so...i have had some "abduction " events happen to me since the early memory,which i have real clarity on but is a point when memory cuts out.I am not UFO obsessed and just accept it happened.